This invention relates to internal combustion engines, and particularly to compact, pressureboosted engines.
Small power plants, for example, those used in ultralight aircraft, are typically two-stroke cycle engines of 15 to 40 brake horsepower and weighing 25 to 60 pounds (11 to 27 kilograms). When compared with four-stroke cycle engines, two-stroke cycle engines are characterized by low reliability and high fuel consumption. Further, two-stroke cycle engines develop effective power only at high crankshaft speeds, thus requiring a mechanical reduction system for a direct-drive output device such as a propeller. Such reduction systems add considerable weight and mechanical complexity to the power plant.
An object of the invention is to provide an improved, light-weight internal combustion engine having a four-stroke cycle and internal pressure boosting.
A further object of the invention is to provide a single, light-weight hemiblock element facilitating the manufacture of a variety of single and multicylinder embodiments of a pressure-boosted internal combustion engine.
Another object of the invention is to provide an improved internal combustion engine having an induction system providing efficient lubrication of internal engine parts.
Another object of the invention is to provide an improved internal combustion engine having a unique, light-weight hemiblock element which incorporates a common boost plenum in multicylinder embodiments.
Yet another object of the invention is to provide an improved light-weight, four-stroke cycle internal combustion engine having internal pressure boosting and efficient flow of working fluid for improved lubrication and cooling.